Vitamin D and Calcium May Reduce Blood Pressure

ORLANDO, Fla.— Higher levels of vitamin D and calcium may keep blood pressure in check, according to new research presented at the National Kidney Foundation Spring Clinical Meetings.

The latest study, by Sarah Bean, an MPH candidate at the University of San Diego, Holly Kramer, MD, MPH, of Loyola University in Chicago, and colleagues adds to a growing body of evidence relating vitamin D status, dietary calcium, and blood pressure.

Vitamin D deficiency impairs calcium homeostasis. Vitamin D regulates calcium via the renin-angiotensin system in the kidneys and its active form influences calcium absorption in the gastrointestinal tract, according to the researchers. Various diets incorporating low-fat dairy products with calcium, such as Dietary Approaches to Stop Hypertension (DASH) diet, have been linked with lower blood pressure.

Using linear regression models, the investigators analyzed the association between serum 25-hydroxyvitamin D—25(OH)D—and blood pressure, then explored the interaction with calcium intake. The models were based on data from 24,844 healthy US adults (average age 37.5; 48.6% male) from the National Health and Examination Survey (NHANES) 2001-2006 who completed dietary recall questionnaires and physical examinations. All of the participants had an estimated glomerular filtration rate of 60 mL/min/1.73m2 and above and were free of kidney disease. On average, systolic blood pressure was 120.3 mm Hg and diastolic blood pressure 69.3 mm Hg.

As 25(OH)D levels increased, systolic blood pressure decreased significantly, even after accounting for calcium intake. In addition, the investigators found a significant interaction between 25(OH)D and calcium intake for diastolic blood pressure.

More research is needed to establish a definitive link between vitamin D, calcium intake, and hypertension. The cross-sectional design of the study prevented determination of causation. Calcium supplementation also was not assessed.